Total hip arthroplasty in patients with ankylosing spondylitis: Midterm radiologic and functional results

Revision total hip arthroplasty in patients with ankylosing spondylitis: Mid-term results

BACKGROUND

Few studies have reported on the outcome of revision total hip arthroplasty (THA) for ankylosing spondylitis (AS). Therefore, we sought to investigate the clinical and radiographic outcomes of revision THA in patients with AS.

HYPOTHESIS

The mid-term outcome of revision THA in AS patients was comparable to conventional revision THA.

MATERIALS AND METHODS

Forty-one patients with AS who underwent revision THA (on a total of 51 hips) between April 2004 and June 2018 were included. The mean follow-up duration was 7.5±3.6 years (3.0-15.8 years). Clinical outcomes were assessed using the Bath Ankylosing Spondylitis Functional Index (BASFI), Harris Hip Score (HHS), and the Western Ontario and McMaster Universities Osteoarthritis (WOMAC) index. Complications were assessed at each follow-up. Radiological outcomes were examined by reviewing postoperative plain radiographs.

RESULTS

Significant improvements were seen in BASFI, HHS, and WOMAC scores (p<0.01). Postoperative combined range of motion (ROM) was 128.9±45.3° (range, 60-300°). Complications included heterotopic ossification, periprosthetic fractures, aseptic loosening, osteolysis, reinfection, residual pain or stiffness, delayed wound healing, numbness, deep vein thrombosis, leg length discrepancy, and posterior dislocation. Five (9.8%) of the 51 hips were treated with re-revision due to aseptic loosening, re-infection, or re-fracture. The incidence of dislocation was 1.9% at 7.5 years. Implant survival for all reasons was estimated to be 96.3% at 5 years, 85.9% at 10 years and 61.0% at 15 years. Forty-two (82.4%) hip revisions were rated "satisfactory" or "very satisfactory" by the patients.

CONCLUSIONS

The mid-term result of revision THA for patients with AS is comparable to conventional revisions in terms of implant survival, despite high complication rates. The benefit-risk ratio of these indications is acceptable but deserves specific information for these patients.

LEVEL OF EVIDENCE

IV; case series.

Intraoperative picture of hip joint lesion in ankylosing spondylitis: data from a retrospective analysis

In population of Russian patients with ankylosing spondylitis (AS), the frequency of clinical manifestations (pain and limitation of functions) of coxitis reaches 56%. Total hip arthroplasty (THA) can be considered as the only alternative that can relieve the suffering of the patient. Radiography and magnetic resonance imaging are widely used methods for assessing structural damage to the hip joint in AS. However, at the moment these methods can’t allow us to fully describe the lifetime changes of these joints. The aim of the study: to analyze the external changes of the femoral heads (HF) and acetabulums during the THA in patients with AS. Materials and methods. The retrospective study included 170 patients with a reliable diagnosis of AS, who met the modified New York criteria of 1984, who were treated in the traumatological and orthopedic department of the V.A. Nasonova Research Institute of Rheumatology in the period from 1998 to 2020, all patients underwent THA as planned. Most of them were male (80.6%). The average age of patients was 38.1±11.3 years and the average duration of the disease since the onset of the first symptoms was 17.0±8.5 years. The duration of pain in hip joints before performing THA is 7.4±4.8 years. The assessment of macroscopic changes in the FH and acetabulum was performed intraoperatively. Results and discussion. Acetabulum protrusion was detected in 108 (63.5%) patients, bone cysts – in 65 (38.2%). Filling of acetabulum with granulation tissue was recorded in 155 (91.2%) patients, presence of osteophytes on its edges – in 153 (90%). Cartilage in the acetabulum was completely absent in 122 (71.8%) patients. FH deformation was detected in 98.2% of cases, erosion in 46.4%. Cartilage on FH was completely absent in 130 (76.5%) patients. In 119 (70%) patients, macroscopic signs of osteonecrosis of FH were found. 79 (46.4%) patients had ankylosis of the hip joint, including fibrous ankylosis – in 77.2% of patients and bone ankylosis – in 22.8%. Conclusion. In patients with AS, the necessity for THA occurs on average after 7.4±4.8 years from the moment of the appearance of first clinical signs of coxitis. In 70% of cases, the macroscopic picture of hip joint lesion was characterized by the development of Avascular necrosis of the femur head (AVNFH), in most patients there was no cartilage in the most loaded segments of acetabulum and FH, in almost half of cases – ankylosis of hip joint and mainly fibrous (77.2%).

The correlation between volumetric bone mineral density and morphological parameters of the proximal femur and clinical outcomes in ankylosing spondylitis patients with hip involvement

Background

To measure volumetric bone mineral density (vBMD) with quantitative computed tomography (QCT) in the proximal femur of ankylosing spondylitis (AS) patients with hip involvement and analyze their correlations with radiographic and clinical parameters.

Methods

Sixty-five AS inpatients were enrolled in this study. The bone mineral density was measured by QCT and dual-energy x-ray absorptiometry (DXA), respectively. The morphological parameters of the proximal femur were measured on digital anteroposterior (AP) radiographs of the pelvis. The correlations between them were analyzed by SPSS software.

Results

The average trabecular vBMD measured at the femoral neck was 136.38 ± 25.58 mg/cm³. According to the BASRI-Hip score, group A consisted of 39 hips (0–2 score) and group B consisted of 26 hips (3–4 score). There were significant differences regarding trabecular CTXA equivalent T-score between group A and B at the femoral neck (p = 0.004); intertrochanteric region (p < 0.001) and greater trochanter (p = 0.001). The trabecular CTXA equivalent T-score at femoral neck had a negative correlation with disease duration (r = − 0.311, p = 0.012) and with CBR (r = − 0.319, p = 0.010).

Conclusions

The low trabecular bone density at the site of the hip was associated with the duration of disease progression and degree of hip involvement. Meanwhile, it had a correlation with hip function status although we failed to confirm a significant relationship between hip vBMD and disease activity.

Total hip arthroplasty in fused hips with spine stiffness in ankylosing spondylitis

Ankylosing spondylitis (AS) is characterized by involvement of the spine and hip joints with progressive stiffness and loss of function. Functional impairment is significant, with spine and hip involvement, and is predominantly seen in the younger age group. Total hip arthroplasty (THA) for fused hips with stiff spines in AS results in considerable improvement of mobility and function. Spine stiffness associated with AS needs evaluation before THA. Preoperative assessment with lateral spine radiographs shows loss of lumbar lordosis. Spinopelvic mobility is reduced with change in sacral slope from sitting to standing less than 10 degrees conforming to the stiff pattern. Care should be taken to reduce acetabular component anteversion at THA in these fused hips, as the posterior pelvic tilt would increase the risk of posterior impingement and anterior dislocation. Fused hips require femoral neck osteotomy, true acetabular floor identification and restoration of the hip center with horizontal and vertical offset to achieve a good functional outcome. Cementless and cemented fixation have shown comparable long-term results with the choice dependent on bone stock at THA. Risks at THA in AS include intraoperative fractures, dislocation, heterotopic ossification, among others. There is significant improvement of functional scores and quality of life following THA in these deserving young individuals with fused hips and spine stiffness.

Automatic segmentation and grading of ankylosing spondylitis on MR images via lightweight hybrid multi-scale convolutional neural network with reinforcement learning

Objective.Ankylosing spondylitis (AS) is a disabling systemic disease that seriously threatens the patient's quality of life. Magnetic resonance imaging (MRI) is highly preferred in clinical diagnosis due to its high contrast and tissue resolution. However, since the uncertainty and intensity inhomogeneous of the AS lesions in MRI, it is still challenging and time-consuming for doctors to quantify the lesions to determine the grade of the patient's condition. Thus, an automatic AS grading method is presented in this study, which integrates the lesion segmentation and grading in a pipeline.Approach. To tackle the large variations in lesion shapes, sizes, and intensity distributions, a lightweight hybrid multi-scale convolutional neural network with reinforcement learning (LHR-Net) is proposed for the AS lesion segmentation. Specifically, the proposed LHR-Net is equipped with the newly proposed hybrid multi-scale module, which consists of multiply convolution layers with different kernel sizes and dilation rates for extracting sufficient multi-scale features. Additionally, a reinforcement learning-based data augmentation module is utilized to deal with the subjects with diffuse and fuzzy lesions that are difficult to segment. Furthermore, to resolve the incomplete segmentation results caused by the inhomogeneous intensity distributions of the AS lesions in MR images, a voxel constraint strategy is proposed to weigh the training voxel labels in the lesion regions. With the accurately segmented AS lesions, automatic AS grading is then performed by a ResNet-50-based classification network.Main results. The performance of the proposed LHR-Net was extensively evaluated on a clinically collected AS MRI dataset, which includes 100 subjects. Dice similarity coefficient (DSC), average surface distance, Hausdorff Distance at95thpercentile (HD95), predicted positive volume, and sensitivity were employed to quantitatively evaluate the segmentation results. The average DSC of the proposed LHR-Net on the AS dataset reached 0.71 on the test set, which outperforms the other state-of-the-art segmentation method by 0.04.Significance. With the accurately segmented lesions, 31 subjects in the test set (38 subjects) were correctly graded, which demonstrates that the proposed LHR-Net might provide a potential automatic method for reproducible computer-assisted diagnosis of AS grading.

Automatic quantification and grading of hip bone marrow oedema in ankylosing spondylitis based on deep learning

OBJECTIVE

This study has developed a new automatic algorithm for the quantificationy and grading of ankylosing spondylitis (AS)-hip arthritis with magnetic resonance imaging (MRI).

METHODS

(1) This study designs a new segmentation network based on deep learning, and a classification network based on deep learning. (2) We train the segmentation model and classification model with the training data and validate the performance of the model. (3) The segmentation results of inflammation in MRI images were obtained and the hip joint was quantified using the segmentation results.

RESULTS

A retrospective analysis was performed on 141 cases; 101 patients were included in the derived cohort and 40 in the validation cohort. In the derivation group, median percentage of bone marrow oedema (BME) for each grade was as follows: 36% for grade 1 (<15%), 42% for grade 2 (15-30%),and 22% for grade 3 (≥30%). The accuracy of 44 cases on 835 AS images was 85.7%. Our model made 31 correct decisions out of 40 AS test cases. This study showed that THE accuracy rate 85.7%.

CONCLUSIONS

An automatic computer-based analysis of MRI has the potential of being a useful method for the diagnosis and grading of AS hip BME.

Primary Total Hip Arthroplasty in Patients With Ankylosing Spondylitis

BACKGROUND

Ankylosing spondylitis (AS) is a common inflammatory spondyloarthropathy with hip involvement in 40% of patients. With the renewed interest in the hip-spine interplay, this study aimed to define long-term outcomes of primary total hip arthroplasty (THA) in the setting of AS.

METHODS

We identified 309 hips (219 patients) with AS treated with primary THA from 1969 to 2018. Mean age was 49 years, 80% were males, and mean body mass index was 28 kg/m². Cumulative incidences of any revision, reoperation, and dislocation were calculated utilizing a competing risk analysis. Harris Hip Scores and complications were also reported. Mean follow-up was 16 years.

RESULTS

The cumulative incidence of any revision after primary THA was 2.3% at 5 years and 17.5% at 20 years. The most common reasons for revision (n = 73) were aseptic loosening (41%), osteolysis/polyethylene (PE) wear (30%, all with conventional PE), and femoral component fracture (8%). The cumulative incidence of dislocation was 1.9% at 5 years and 2.9% at 20 years. Younger age was associated with increased risk of revision (hazard ratio (HR) = 1.3, P < .01) and reoperation (HR = 1.2, P < .01), but not dislocation (HR = 0.7, P = .1). Twenty-eight hips (9%) experienced a postoperative complication not requiring reoperation. The mean Harris Hip Score improved from 51 to 76 after THA (P < .001).

CONCLUSION

In this series of 309 primary THAs in patients with AS, the 20-year cumulative incidence of any revision after primary THA was 17.5%. Aseptic loosening, osteolysis/PE wear, and femoral component fracture were the most common reasons for revision. Notably, the cumulative incidence of dislocation at 20 years was only 2.9%.

LEVEL OF EVIDENCE

Level IV.

Surgical strategies in management of ankylosed bilateral hips and knees in crouched posture

A 26-year-old wheelchair-bound man was brought to our institute with progressive painful deformity of both lower limbs involving bilateral hip and knee for the past 5 years. The patient was wheelchair-bound for the past 18 months. He was only able to crawl to meet his locomotor demands. On examination, the patient was in a crouched posture with mild kyphosis at the thoracolumbar region and ankylosis of bilateral hip and knee in an unfavourable position. Radiological and serological evaluation diagnosed him to be a case of neglected ankylosing spondylosis. We planned for arthroplasty of the bilateral hip and knee for correcting his posture and to regain his locomotor ability. The severity of the deformity mandated extensive releases and the handling of neurovascular structures. Hence, a holistic treatment plan with various surgical strategies was devised to manage his deformities. The patient made a good recovery and regained his locomotor ability without any major complications at a 2-year follow-up.

Revision Total Hip Arthroplasty in Patients With Ankylosing Spondylitis: Long-Term Results

BACKGROUND

Ankylosing spondylitis (AS) is a common inflammatory spondyloarthropathy with hip involvement in 40% of patients. With the recent interest in the hip-spine interplay, the purpose of this study was to define the long-term outcomes of revision total hip arthroplasty (THA) in the setting of AS.

METHODS

174 hips in patients with AS treated with revision THA from 1969 to 2016 were identified. Mean age at revision THA was 53 years and 76% were male. Cumulative incidences of any re-revision, reoperation, and dislocation were calculated using a competing risk analysis. Mean follow-up was 13 years.

RESULTS

The cumulative incidence of any re-revision after index revision THA was 7% at 5 years and 36% at 20 years. Cumulative incidence of any reoperation was 9% at 5 years and 38% at 20 years. Cumulative incidence of dislocation was 6% at 5 years and 8% at 20 years. Revision THAs performed with contemporary implants (2000-2016) had a lower but statistically nonsignificant cumulative incidence of any re-revision when compared with historical implants (before 2000) at 5 years (5% vs 8%), 10 years (11% vs 18%), and 15 years (11% vs 38%) (hazard ratio, 0.47; 95% confidence interval, 0.17-1.33; P = .016).

CONCLUSION

In this large series of 174 revision THAs in patients with AS, the cumulative incidence of dislocation was 8% at 20 years. The 20-year cumulative incidence of any re-revision was 36%, which is similar to reported rates in patients with comparable demographic features without AS.

LEVEL OF EVIDENCE

Level IV.

Does the Femoral Head Size Influence Outcomes After Uncemented Total Hip Arthroplasty for Fused Hips? A Prospective Study in Ankylosing Spondylitis

BACKGROUND

Uncemented total hip arthroplasty (THA) with large size femoral heads have shown greater advantage with good stability, range of motion and decreased dislocation rate in ankylosing spondylitis (AS). Meticulous planning is needed to address the unique surgical challenges in such patients with fused hip and spinal deformity.

MATERIALS AND METHODS

Thirty fivefused hip joints in twenty-five AS patients who underwent uncemented THA (April 2014 to December 2016) were included in our prospective study and were followed up for a minimum period of 36 months. Pain relief, functional improvement and patient satisfaction were statistically assessed using "Visual Analogue Score" (VAS), "Harris Hip Score" (HHS) and "AJRI 10-Point Satisfaction Score" (A10PSS), respectively.

RESULTS

The overall mean preoperative VAS improved from 6.9 ± 1.5 to 1.5 ± 1, HHS improved from 50.0 ± 12 to 88.4 ± 7.8 and A10PSS improved from 2.2 ± 1.2 to 7.6 ± 0.8. Our study results were significant with zero dislocation and good functional score in comparison to the other available studies in literature. First subdivision study in AS patients with bilateral THA performed better than unilateral THA. Second subdivision study showed no significant statistical difference in terms of VAS, HHS, A10PSS and dislocation rate in relation to femoral head size between 32 mm, 36 mm and 40 mm.

CONCLUSION

Uncemented THA with large size femoral head equal or greater than 32 mm provides better stability and good functional outcome with less dislocation rate in comparison to older studies of literature with femoral head size less than 32 mm.

LEVEL OF EVIDENCE

A Level II study. (Data collected from the ongoing prospective study) (https://www.spine.org/Documents/LevelsofEvidenceFinal.pdf).

Spondyloarthritis is associated with higher healthcare utilization and complication rates after primary total knee or total hip arthroplasty

Our objective was to assess healthcare utilization and complication rates after primary total knee/hip arthroplasty (TKA/THA) in people with spondyloarthritis (SpA) compared with people without SpA. We performed multivariable-adjusted logistic regression using the 1998-2014 US National Inpatient Sample (NIS), adjusted for age, race/ethnicity, gender, income, Deyo-Charlson comorbidity index, insurance payer, and the underlying diagnosis. The primary THA cohort consisted of 4,116,484 THAs (1.7% with SpA) and primary TKA cohort of 8,127,282 TKAs (1% with SpA). Compared with people without SpA, people with SpA had higher odds ratio (OR (95% confidence interval (CI)) of the following post-THA and post-TKA, respectively: (1) discharge to care facility, 1.16 (1.12, 1.21) and 1.14 (1.11, 1.18); (2) hospital stay > 3 days, 1.15 (1.11, 1.20) and 1.05 (1.01, 1.10); and (3) transfusion, 1.16 (1.12, 1.21) and 1.10 (1.05, 1.14); but lower odds of (1) mortality, 0.78 (0.64, 0.96) and 0.40 (0.19, 0.84); and (2) hospital charges above the median, 0.49 (0.46, 0.53) and 0.48 (0.45, 0.51). SpA was associated with higher odds of implant infection, 3.02 (2.27, 4.03) post-TKA, not post-THA. In-hospital revision rate did not differ. People with SpA utilize more healthcare services and have more complications post-THA/TKA. Interventions to reduce complications and associated utilization are needed. Key Points • People with spondyloarthritis utilized more healthcare services and had a higher risk of transfusion post-THA/TKA, compared with people without spondyloarthritis. • Spondyloarthritis was associated with lower in-hospital mortality rates after THA/TKA. • Spondyloarthritis was associated with a higher risk of implant infection after TKA, but not THA. • A pre-operative discussion with people with spondyloarthritis of possibly higher implant infection after TKA could lead to a more informed consent.

Bilateral total hip arthroplasty in ankylosing spondylitis: a systematic review

Ankylosing Spondylitis (AS) can commonly involve the hip joint and cause significant mobility problems. Total hip arthroplasty (THA) on a single side alone will not restore mobility in patients with bilateral disease.We performed a systematic review of the available literature to determine the changes in objective outcome measures and complications of bilateral THA in patients with advanced AS. Four studies, a total of 114 THAs, were included in the study. The average patient age was 32.9 years and the average follow-up time was 59.5 months.All studies reported a significant improvement in hip function, patient satisfaction and patient mobility following bilateral THA. Harris Hip Score (HHS) improved by a mean of 60.6 points post-operatively.Complications included five intra-operative fractures (4.4%) and three transient nerve palsies (2.6%). There were two dislocations (1.8%) that were successfully managed with closed reduction. Seven hips required revision, with the most common cause being aseptic loosening. Twelve hips (10.5%) developed heterotopic ossification consistent with Brooker Class 1 or 2 with no reports of re-ankylosis.This review suggests that bilateral THA is a safe and effective treatment of advanced hip disease in AS. Attention must be paid to the highly demanding technical aspects of this procedure to reduce the risk of significant complications.Debate still exists on the ideal prosthesis, fixation method and approach to use but this review presents data from several series of uncemented prostheses that have good post-operative results. Cite this article: EFORT Open Rev 2019;4:476-481. DOI: 10.1302/2058-5241.4.180047.

The effects of total hip arthroplasty in treating hip bony fusion in young and middle-aged patients with ankylosing spondylitis

Background

This study aims to investigate the curative effects of total hip arthroplasty (THA) in treating hip bony fusion for young and middle-aged patients with ankylosing spondylitis (AS).

Methods

The clinical data of 26 young and middle-aged patients with AS (31 coxae), who were treated with THA and followed-up for more than 3 years in the period between February 1998 and May 2013, were retrospectively analyzed. Among these patients, 22 patients were male (25 coxae) and 4 patients were female (6 coxae). Patients’ age ranged within 19–50 years old, with an average of 31.5 years old. The intervals from arthroplasty to the occurrence of hip joint lesions caused by AS ranged within 2–26 years, with an average of 11.2 years. The average Harris score before the surgery was 19.0 ± 11.5 points.

Results

Femoral proximal cleavage fracture occurred in one coxa during the surgery and was fixed by the steel wire cerclage. Sciatic nerve traction injury occurred in one coxa after the surgery, which recovered after 6 months. Posterior hip dislocation occurred in one coxa and was immediately treated with manual reduction. All patients were followed-up, and follow-up duration ranged within 36–123 months, with an average of 46.5 months. In the last follow-up, the average Harris score was 87.1 ± 13.1 points, total passive range of motion was 215.0 ± 22.0°, and passive range of flexion was 90.8 ± 9.3°. All these indexes significantly increased compared with pretreatment (P < 0.01). A periacetabular radiolucent line occurred in one coxa with a width of < 2 mm, and no femoral radiolucent line was found during follow-ups in any patient. Heterotopic ossification occurred in four coxae.

Conclusion

THA treatment for hip bony fusion caused by AS can achieve satisfactory hip function recovery and excellent prosthesis survival rate.

Complications of Total Hip Arthroplasty in Patients With Ankylosing Spondylitis

OBJECTIVE

To compare the risks of complications of primary total hip arthroplasty (THA) between patients with ankylosing spondylitis (AS) and those without AS.

METHODS

In this population-based study, we examined data from 1999 to 2013 of US Medicare beneficiaries (ages <75 years old) with AS and a comparison group without AS who had undergone primary THA. Complications were based on the Centers for Medicare & Medicaid Services 2013 THA Complication Measure, which included myocardial infarction, pneumonia, or sepsis within 7 days; surgical site bleeding, pulmonary embolus, or venous thrombosis within 30 days; or mechanical complications or local infection within 90 days. Mortality within 90 days, revision arthroplasty within 1 year, long length of stay, discharge to a care facility, and readmission within 90 days were also examined.

RESULTS

The study included 2,773 patients with AS and 107,341 patients without AS who had THA. Perioperative complications, 30-day complications, and local infections were rare in both groups (<1%). Mechanical complications and revision arthroplasty were uncommon in both groups. Ninety-day mortality was lower among patients with AS than those without AS (0.36% versus 0.7%). Patients with AS were more likely to be discharged to a care facility, and slightly more likely to have a long length of stay. Likelihood of a long stay was lower at hospitals that performed ≥100 THAs per year, but other complications were not associated with hospital volume.

CONCLUSION

Complications after primary THA are uncommon in patients with AS and similar in frequency to those without AS. Ninety-day mortality was lower among patients with AS.

Long-term Outcomes of Cemented Total Hip Arthroplasty in Patients with Ankylosing Spondylitis at a Minimum Follow-up of 10 Years

Purpose

This study was performed to evaluate long-term clinical and radiologic outcomes of cemented total hip arthroplasty in patients with ankylosing spondylitis.

Materials and Methods

A retrospective study of 12 patients (16 cases) diagnosed with ankylosing spondylitis undergoing total hip arthroplasty with cemented femoral stem from November 2002 to January 2006 with a minimum follow up of 10 years. Clinical outcomes were assessed using Harris Hip Scores and measures of pain and range of motion. Radiologic outcomes were assessed with serial plain X-ray. Fixation and stability of implant, enthesopathy of ischium and development of heterotopic ossification were also evaluated.

Results

Mean Harris Hip Scores significantly improved from pre-operative levels (58 points; range, 39–81 points) to post-operative (92 points; range, 68–100 points). Mean flexion contracture levels decreased from preoperative (13°) to post-operative (5°), and mean post-operative range of motion improved 106° compared to preoperative levels. No newly developed osteolysis lesions or implant loosening were observed in last follow up X-rays. One heterotopic ossification and one greater trochanter fracture were observed. Greater trochanter fracture was treated conservatively, and was resulted in bony union. No patients underwent revisions.

Conclusion

This study revealed positive long-term clinical and radiologic outcomes following total hip arthroplasty with cemented femoral stems in patients with ankylosing spondylitis patients.

Incident osteoarthritis and osteoarthritis-related joint replacement surgery in patients with ankylosing spondylitis: A secondary cohort analysis of a nationwide, population-based health claims database

BACKGROUND

Ankylosing spondylitis (AS) might be associated with an increased risk of secondary osteoarthritis. However, there is a lack of studies assessing its impact on osteoarthritis-related surgery. The aim of this secondary cohort study was to investigate the risk of symptomatic osteoarthritis and osteoarthritis-related surgery, including total hip replacement surgery (THRS) and total knee replacement surgery (TKRS) in patients with AS.

METHODS

Using the Taiwan's National Health Insurance Research Database, we identified 3,462 patients with AS between 2000 and 2012. A comparison cohort was assembled consisting of five patients without AS, based on frequency matching for sex, 10-year age interval, and index year, for each patient with AS. Both groups were followed until diagnosis of the study outcomes or the end of the follow-up period.

RESULTS

Male patients with AS exhibited a significantly higher incidence of osteoarthritis (adjusted incidence rate ratio [IRR] 1.43; P < 0.001), THRS (adjusted IRR 12.59; P < 0.001), and TKRS (adjusted IRR 1.89; P = 0.036). Moreover, analyses stratified by age group (20-39 years versus 40-80 years) indicated a high IRR (adjusted IRR 27.66; P <0.001) for THRS among younger patients with AS.

CONCLUSIONS

Male patients with AS had a significant higher risk of developing osteoarthritis, and receiving THRS and TKRS. Young patients with AS also showed a significant higher risk of receiving THRS.

Ankylosing Spondylitis Increases Perioperative and Postoperative Complications After Total Hip Arthroplasty

BACKGROUND

Ankylosing spondylitis (AS) is a chronic autoimmune spondyloarthropathy that primarily affects the axial spine and hips. Progressive disease leads to pronounced spinal kyphosis, positive sagittal balance, and altered biomechanics. The purpose of this study is to determine the complication profile of patients with AS undergoing total hip arthroplasty (THA).

METHODS

The Medicare sample was searched from 2005 to 2012 yielding 1006 patients with AS who subsequently underwent THA. Risk ratios (RRs) with 95% confidence intervals (CIs) were calculated for 90-day, 2-year, and the final postoperative follow-up for complications including hip dislocation, periprosthetic fracture, wound complication, revision THA, and postoperative infection.

RESULTS

Compared to controls, AS patients had an RR of 2.50 (CI, 1.04-5.99) of THA component breakage at 90-days post-operatively and 1.99 (CI, 1.10-3.59) at 2-years. The RR of periprosthetic hip dislocation was elevated at 90 days (1.44; CI, 0.93-2.22) and significantly increased at 2-years (1.67; CI, 1.25-2.23) and overall follow-up (1.49; CI, 1.14-1.93). Similarly, the RR for THA revision was elevated at 90-days (1.46; CI, 0.97-2.18) and significantly increased at 2-years (1.69; CI, 1.33-2.14) and overall follow-up (1.51; CI, 1.23-1.85).

CONCLUSION

Patients with AS are at increased risk for complications after THA. Altered biomechanics from a rigid, kyphotic spine place increased demand on the hip joints. The elevated perioperative and postoperative risks should be discussed preoperatively, and these patients may require increased preoperative medical optimization as well as possible changes in component selection and position to compensate for altered spinopelvic biomechanics.